Solid ink or phase change ink imaging devices, hereafter called solid ink printers for convenience, encompass various imaging devices, such as printers and multi-function devices. These printers offer many advantages over other types of image generating devices, such as laser and aqueous inkjet imaging devices. Solid ink or phase change ink printers conventionally receive ink in a solid form, either as pellets or as ink sticks. A color printer typically uses four colors of ink (yellow, cyan, magenta, and black).
The solid ink pellets or ink sticks, hereafter referred to as ink, sticks, or ink sticks, are delivered to a melting device, which is typically coupled to an ink loader, for conversion of the solid ink to a liquid. A typical ink loader typically includes multiple feed channels, one for each color of ink used in the imaging device. The ink for a particular color is placed in an insertion opening in the feed channel and then either gravity fed or urged by a conveyor or spring loaded pusher along the feed channel toward the melting device. The melting device heats the solid ink impinging on it and melts it into a liquid for delivery to a print head for jetting onto a recording medium or intermediate transfer surface.
The feed channel insertion openings may be covered by a key plate with a keyed opening for each feed channel. The keyed openings help ensure a printer user places the correct sticks into a feed channel. Each keyed opening of the key plate has a unique shape. The ink sticks of the color for that feed channel have a shape corresponding to the shape of the keyed opening. The keyed openings and corresponding stick shapes exclude from each ink feed channel sticks of all colors except the ink sticks of the proper color for that feed channel. Unique keying shapes for other factors are also being employed to exclude sticks from being inserted that are not correctly formulated or intended for different printer models.
Solid ink printers significantly differ from ink cartridge or toner printers because they need not be exhausted before additional solid ink is added to the feed channel. Specifically, ink cartridges and toner cartridges should be exhausted before another cartridge is installed so as not to waste ink or toner in a partially emptied cartridge. These cartridges may be typically returned to the manufacturer or other source to be refilled. Solid ink, on the other hand, may be stored on the premises and installed a stick at a time or as a group of pellets. Because the entire solid ink unit is consumed in the printing process, no housing or other component survives for disposal or return to the manufacturer.
The requirement that the ink sticks remain solid until they impinge upon the melting assembly does present some challenges not present in ink cartridge and toner cartridge printers. Because the ink loader is above the ambient room temperature, the ink softens. The softened ink requires more force to be applied to the ink to overcome the increased friction. Additionally, a limit exists for the temperature level in an ink loader in order to prevent the ink from becoming too soft and losing its shape in the loader.
The components of a solid ink printer must be arranged to perform the functions of transporting the solid ink to a melting assembly, providing the molten ink to one or more print heads for ejection onto an image receiving member, affixing the ink image to media, and delivering the media bearing the image to an output tray. The requirements of these functions affect the geometry of the printer, the arrangement of the components, and the size of the printer. Consequently, the various subsystems of a solid ink printer compete for placement and location within a printer. Therefore, solid ink transport methods that enable more flexibility in routing and arrangement would facilitate the overall design of solid ink printers.